Understanding Linux Filesystem

I'll start by looking at the filesystem, in Void Linux

• /usr/bin : The binary path (symlinks: /bin /sbin)
• /usr/lib : The library path (symlinks: /lib /lib64)
  • Includes Python in, because many programs depend on Python runtime; in /usr/lib/python3
  • Includes C/C++ Libraries in /usr/lib/gcc/<arch-kernel-libc>
  • The root folder includes the C shared libraries
  • Subfolders include package specific libraries, like Python, GCC, etc.
  • Some applications (especially in /usr/local/lib) put files in the root folder too
• /usr/lib32 : The multilib library path (symlinks: /lib32)
• /boot : The boot files - EFI and GRUB
• /dev : A ton of interfaces
  • ??
• /etc : Configurations
  • Commonplace files include
    • hosts : Stores system host name
    • passwd : Stores user ID mappings
    • shadow : Stores user passwords
    • sudoers : Stores sudo configuration
    • hostname : Stores FQDN and partial hostname mappings to IPs, aside from DNS
    • resolv.conf : Stores DNS Resolver configuration
    • nsswitch.conf : Sets the order of host resolution by system library functions
• /home/username : User home directory
  • Stores user specific software configurations in .config and in the root folder
  • Stores local software files in .local, but in a more casual style compared to /usr/local
  • Stores software cache in .cache and in the root folder
  • Flatpak uses .var folder to store user specific app installations
  • Commonplace files include
    • X11 Related: .XAuthority, .xprofile, .xinitrc
    • Bash Related: .bashrc, .bash_history, .bash_profile, .bash_logout
    • Git Config: .gitconfig
    • Miscellaneous: .python_history
    • I don't know what: .inputrc, .lesshst, .gtkrc-2.0, .profile, .wget-hsts
• /proc : A ton of interfaces
  • ??
• /root : Root home directory
• /sys : A ton of interfaces
  • ??
• /run : A ton of runtime interfaces
  • ??
• Empty standard directories : /media /mnt /opt /srv
• /tmp : Temporary directory
• Other /usr Subdirectories:
  • /usr/include
  • /usr/libexec
  • /usr/local : The manual installations as opposed to package manager installations
    • Has /usr/local/bin, /usr/local/lib, /usr/local/include and /usr/local/share
  • /usr/share : Shared assets
    • Includes fonts, applications, icons, ...
  • /usr/src : Empty folder
• /var : A ton of runtime files
  • ??